[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240227013546.15769-5-zev@bewilderbeest.net>
Date: Mon, 26 Feb 2024 17:35:41 -0800
From: Zev Weiss <zev@...ilderbeest.net>
To: Russell King <linux@...linux.org.uk>,
linux-parisc@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Helge Deller <deller@....de>,
Florent Revest <revest@...omium.org>
Cc: Zev Weiss <zev@...ilderbeest.net>,
"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
"Borislav Petkov (AMD)" <bp@...en8.de>,
Yin Fengwei <fengwei.yin@...el.com>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>,
Yang Shi <yang@...amperecomputing.com>,
Rick Edgecombe <rick.p.edgecombe@...el.com>,
Oleg Nesterov <oleg@...hat.com>,
David Hildenbrand <david@...hat.com>,
Stefan Roesch <shr@...kernel.io>,
Josh Triplett <josh@...htriplett.org>,
Ondrej Mosnacek <omosnace@...hat.com>,
Miguel Ojeda <ojeda@...nel.org>,
linux-kernel@...r.kernel.org,
openbmc@...ts.ozlabs.org,
Sam James <sam@...too.org>,
stable@...r.kernel.org
Subject: [PATCH RESEND 1/2] prctl: Generalize PR_SET_MDWE support check to be per-arch
There exist systems other than PARISC where MDWE may not be feasible
to support; rather than cluttering up the generic code with additional
arch-specific logic let's add a generic function for checking MDWE
support and allow each arch to override it as needed.
Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
Cc: <stable@...r.kernel.org> # v6.3+
---
arch/parisc/include/asm/mman.h | 14 ++++++++++++++
include/linux/mman.h | 8 ++++++++
kernel/sys.c | 7 +++++--
3 files changed, 27 insertions(+), 2 deletions(-)
create mode 100644 arch/parisc/include/asm/mman.h
diff --git a/arch/parisc/include/asm/mman.h b/arch/parisc/include/asm/mman.h
new file mode 100644
index 000000000000..47c5a1991d10
--- /dev/null
+++ b/arch/parisc/include/asm/mman.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MMAN_H__
+#define __ASM_MMAN_H__
+
+#include <uapi/asm/mman.h>
+
+/* PARISC cannot allow mdwe as it needs writable stacks */
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+ return false;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+
+#endif /* __ASM_MMAN_H__ */
diff --git a/include/linux/mman.h b/include/linux/mman.h
index dc7048824be8..bcb201ab7a41 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -162,6 +162,14 @@ calc_vm_flag_bits(unsigned long flags)
unsigned long vm_commit_limit(void);
+#ifndef arch_memory_deny_write_exec_supported
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+ return true;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+#endif
+
/*
* Denies creating a writable executable mapping or gaining executable permissions.
*
diff --git a/kernel/sys.c b/kernel/sys.c
index f8e543f1e38a..8bb106a56b3a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2408,8 +2408,11 @@ static inline int prctl_set_mdwe(unsigned long bits, unsigned long arg3,
if (bits & PR_MDWE_NO_INHERIT && !(bits & PR_MDWE_REFUSE_EXEC_GAIN))
return -EINVAL;
- /* PARISC cannot allow mdwe as it needs writable stacks */
- if (IS_ENABLED(CONFIG_PARISC))
+ /*
+ * EOPNOTSUPP might be more appropriate here in principle, but
+ * existing userspace depends on EINVAL specifically.
+ */
+ if (!arch_memory_deny_write_exec_supported())
return -EINVAL;
current_bits = get_current_mdwe();
--
2.43.2
Powered by blists - more mailing lists